The Federal Government will develop a new anti-extremism strategy, appoint a national terrorism coordinator and change Australia's system of terror threat alerts, in response to a review of counter-terrorism measures.Prime Minister Tony Abbott will announce the changes in a speech on national security later today, based on the recommendations of a counter-terrorism review commissioned last August."Australia has entered a new, long-term era of heightened terrorism threat, with a much more significant home-grown element," Mr Abbott will say in his national security address.The Prime Minister will also quote an increase in the number of Australians returning from conflicts in Syria and Iraq, to back up his argument that "the number of potential terrorists ... who may live in our midst, is rising"."Over 30 foreign fighters have returned to Australia and at least 140 people in Australia are actively supporting extremist groups," Mr Abbott will say."Thousands of young and vulnerable people in the community are susceptible to radicalisation."The Government has previously said there are 90 Australians fighting in Syria and northern Iraq.Mr Abbott will also accept a recommendation that Australia simplify the current system of terror alert warnings, which classifies threats as low, medium, high or extreme.Recommendations dealing with the long-term funding for security agencies will be considered separately.Personal freedom and community safety need to balance: AbbottIn response to a joint Commonwealth and New South Wales report into last December's Sydney siege, Mr Abbott yesterday warned that an "era of terror" meant Australia would need to reconsider "where it draws the balance" between personal freedom and community safety."Precisely where we draw the line in the era of terrorism will need to be reconsidered," he said."We need to ask ourselves, at what stage do we need to change the tipping point from protection of the individual to the safety of the community?"That report, released yesterday, found that the decisions of various government agencies which dealt siege gunman Man Haron Monis were "reasonable".But Mr Abbott said the community had been let down by the system which allowed Monis to remain at large, despite the serious criminal charges he was facing."Plainly, this monster should not have been in our community," he said.Mr Abbott foreshadowed tougher visa, citizenship and immigration laws as well as measures to combat the spread illegal firearms in response, promising he would have more to say about those measures in today's speech.Labor and Liberal are in this together: ShortenOpposition Leader Bill Shorten said Labor was keen to work with the Government, and would accept the Government's offer of a briefing on intended changes."When it comes to keeping Australians safe, Labor and Liberal are in this together and we will work together in a considered way," Mr Shorten said.The Opposition Leader said he would be happy to examine the Prime Minister's proposals, but has cautioned against going too far."I don't believe our nation can only be safe if we get rid of the liberties of people, nor do I believe that the liberties of people in every sense should trump national security," Mr Shorten said.Liberal Democratic Senator David Leyonhjelm warned against using the threat of terror to justify laws which might restrict ordinary peoples' freedom.Mr Leyonhjelm said he supported targeted measures but remained wary. "You shouldn't give up liberty for safety and in fact you don't need to," he said."We can achieve safety from terrorists - the people who threaten us - without giving up our liberties."